en Medical Physics Medical Physics تحقيق بديع Original Research <div style="text-align: justify;">Background: Stereotactic body radiotherapy (SBRT) is an emerging treatment option which allows for extreme hypofractionation using modern technologies, because the low &alpha;/&beta;-ratio favors the use of high dose per fraction in prostate cancer. There is a need for more data about SBRT. We provide a long-term update of SBRT clinical outcome using CyberKnife for the treatment of localized prostate cancer. Materials and Methods: This study was based on a retrospective analysis of 43 patients treated with SBRT using CyberKnife for localized prostate cancer (23.3% in low risk, 67.4% in intermediate risk and 9.3% in high risk). The target volume included the prostate with or without the seminal vesicles depending on the risk stratification and uncertainty margins that are kept at 3-5 mm. Total dose of 36.25 Gy in 5 fractions of 7.25 Gy were administered. Results: 43 patients with a median 73.6 months (range, 14 to 119 months) follow-up were analyzed. There was three biochemical failure (BCF). Eight-year BCF free survival and overall survival were 92.0% and 73.1%, respectively. Median PSA decline rates were -0.301, -0.191 and -0.115 ng/mL/month, respectively, for durations of 1, 2 and 3 years after radiotherapy and has remained plateau. Median PSA nadir was 0.27 ng/mL at median 38 months and PSA bounce (median 0.33 ng/mL) occurred in 32.6% (n = 14) of patients at median 19 months after SBRT. There was no grade 3 acute and late toxicity. Conclusion: Our long-term experience with SBRT using CyberKnife for localized prostate cancer demonstrates favorable efficacy and toxicity.</div> CyberKnife, prostate cancer, stereotactic body radiotherapy, prostate-specific antigen, radiotherapy, hypofractionation. 383 388 http://ijrr.com/browse.php?a_code=A-10-2055-26&slc_lang=en&sid=1 H.J. Kim cancerovercome@gmail.com 7900319475328460017316 7900319475328460017316 Yes Department of Radiation Oncology, Inha University Hospital, Inha University of Medicine, Inchon, Korea J.S. Lee 7900319475328460017317 7900319475328460017317 No Department of Radiation Oncology, Inha University Hospital, Inha University of Medicine, Inchon, Korea W.C. Kim 7900319475328460017318 7900319475328460017318 No Department of Radiation Oncology, Inha University Hospital, Inha University of Medicine, Inchon, Korea